Markdown Style changes after HA 12.1 Update

no, well, maybe also, but this was give as solution

      - type: markdown
        card_mod:
          style:
            .: |
              ha-card {
                overflow-y: scroll;
                max-height: 700px;
              }

            ha-markdown $: |
              td {
                padding: 0px !important;
              }

add border: none !important if you dont want the borders and dont use a theme var (which is always better and more robust)
anyways, lets not repeat that whole topic here…