2021.6.5 does repair the restful sensor issue in 2021.6.4 but it breaks webhooks, telegram (using webhooks) and the Daikin climate integrations.
Back to 2021.6.3 and two restarts later and everything appears to be ok.
Daikin issue: Daikin AC Integration with BRP072C42 , Unexpected error creating device · Issue #51919 · home-assistant/core · GitHub
Webhook issue (open since 2021.3 apparently) Webhook Setup failed in HA 2021.3 · Issue #47399 · home-assistant/core · GitHub
What has happened to the logs?
It takes nearly 30 seconds to show the Core-log and 45 seconds to show the Supervisor-log. DNS-log and Multicast-log are also slow.
The only logs that are showing instant are Host-log and Audio-log.
There is no error in Supervisor-log, everything is green.
In earlier Home Assistant versions all logs are showing instant.
I am using an Pi 4 4GB with Home Assistant OS 6.0, Core 2021.6.5 and Supervisor 2021.06.0 on an M.2 SSD.
It’s not happening to me, everything is immediate.
Rpi4 8Gb boot ssd HAOS 6.0, Core 2021.6.5 a Supervisor 2021.06.0.
After upgrad to core-2021.6.4 and supervisor 2021.06.03 hassio restarts or the interface becomes unavailable
21-06-16 15:20:35 WARNING (MainThread) [supervisor.misc.tasks] Watchdog miss API response from Home Assistant
21-06-16 15:21:15 INFO (MainThread) [supervisor.resolution.evaluate] Starting system evaluation with state CoreState.RUNNING
21-06-16 15:21:17 INFO (MainThread) [supervisor.resolution.evaluate] System evaluation complete
21-06-16 15:22:45 ERROR (MainThread) [supervisor.misc.tasks] Watchdog found a problem with Home Assistant API!
21-06-16 15:22:45 INFO (SyncWorker_3) [supervisor.docker.interface] Restarting ghcr.io/home-assistant/raspberrypi3-64-homeassistant
21-06-16 15:22:51 INFO (MainThread) [supervisor.homeassistant.core] Wait until Home Assistant is ready
21-06-16 15:23:45 INFO (MainThread) [supervisor.resolution.evaluate] Starting system evaluation with state CoreState.RUNNING
21-06-16 15:23:47 INFO (MainThread) [supervisor.resolution.evaluate] System evaluation complete
21-06-16 15:25:24 INFO (MainThread) [supervisor.homeassistant.core] Detect a running Home Assistant instance
21-06-16 15:25:25 WARNING (MainThread) [supervisor.addons.options] Option ‘anonymous’ does not exist in the schema for Mosquitto broker (core_mosquitto)
Fix your Mosquitto addon configuration. You have old configuration options that are no longer supported. Check the addon docs for the current supported config.
That’s very likely not causing your other issues though.
Upgrading from core-2021.6.4 to core-2021.6.5 is failing with the errors below in the logs.
21-06-17 09:23:45 INFO (SyncWorker_0) [supervisor.docker.interface] Downloading docker image ghcr.io/home-assistant/odroid-n2-homeassistant with tag 2021.6.5.
21-06-17 09:24:16 ERROR (SyncWorker_0) [supervisor.docker.interface] Can’t install ghcr.io/home-assistant/odroid-n2-homeassistant:2021.6.5: 404 Client Error for http+docker://localhost/v1.41/images/ghcr.io/home-assistant/odroid-n2-homeassistant:2021.6.5/json: Not Found (“no such image: ghcr.io/home-assistant/odroid-n2-homeassistant:2021.6.5: No such image: ghcr.io/home-assistant/odroid-n2-homeassistant:2021.6.5”)
404 error generally means the disk is full
There’s 122GB of eMMC disk still available on the host. So it’s not full by any stretch, that’s 96% of the available disk.
Given the updatespeed of homeassistant you will be full by the end of the year 
Problem now resolved, with no changes on my side to make it happen so I"m putting it down to the magic of internet routing having a temporary hissy fit…
hi @tiimsvk can you please be more specific on how you fixed this? i tried to copy the climate.py file over and i added a few lines to the init.py but it still does not work. any tips would be appreciated
Found out meanwhile? I also can´t keep going in terms of syntax with the docs Home Assistant Frontend - Home Assistant 
How to disable polling (is there a service?) for integrations currently NOT being controlled using the UI (but instead using YAML)? For example AndroidTV (Android Debug Bridge - Home Assistant).
In the end I´d like to do achieve something like
“IF (device = online) DO enable integration”
“IF (device = offline) DO disable integration”
thinking of two simple automations just to work around tons of errors in HA log due to devices being offline and constantly polled (many integrations do that).
Uninstall all local tuya reposietaries and add rospogrigio repository.
And compared in app “arxis merge” repositaries and add missing to the rospogrigio repository.
and restart server
Yes, the same issue over here 
This is what the wind direction history graph used to look like:
And this is how it looks now:
When I hover over the black part with my mouse, it turns white and does not recover anymore. It started when I upgraded from core-2021.5.4 to core-2021.6.5 and to OS 6.0 about 5 days ago. Today I upgraded to core-2021.6.6, but the problem persists. The problem occurs on 2 different windows computers using Chrome and in both the Android and IOS companion apps. In the windows computers it only started after re-loading the front-end. Any tips are welcome. I’m really clueless on how to tackle this issue.
Anyone else seeing the Updater binary sensor stuck On? I started noticing this with 2021.6.5.
I’m on 2021.6.6 (just updated), the latest docker image homeassistant/home-assistant:stable).
Sorry if this was covered somewhere – it’s difficult to search “updater” without getting lots of hits.
I have the same issue.
Not on core 2021.6.6 in venv- last activity seen 3 weeks ago 
Best, JR
One thing I noticed:
https://updater.home-assistant.io
Returns:
{“release-notes”:“https://www.home-assistant.io/latest-release-notes/",“version”:"2021.4.6”}
EDIT: But updater.binary_sensor (looking at core/homeassistant/components/updater/init.py) uses: https://www.home-assistant.io/version.json, which returns 2021.6.6 as “current_version”.
So never mind, that’s not the issue