I used original 40MHz, default 10MHz and 1MHz. It has no influence on the picture. Mine device is from Aliexpress, but it looks the same.
Odd thing is that with old library it works flawlessly - except the slow refresh, but that is the same with mipi_spi.
It looks that the drawing is split to several sectors and it can be artifact from that.
[14:11:06.349][V][display.mipi_spi:510]: Drawing from line 0 took 9ms
[14:11:06.351][V][display.mipi_spi:515]: x_low 0, y_low 0, x_high 319, y_high 20
[14:11:06.353][V][display.mipi_spi:297]: Set addr 0/0, 319/21
[14:11:06.354][V][display.mipi_spi:244]: Command 2B, length 4, bytes 00.22.00.37
[14:11:06.356][V][display.mipi_spi:244]: Command 2A, length 4, bytes 00.00.01.3F
[14:11:06.359][V][display.mipi_spi:244]: Command 2C, length 0, bytes
[14:11:06.369][V][display.mipi_spi:532]: Write to display took 17ms
[14:11:06.370][D][display:428]: Display update running
[14:11:06.377][V][display.mipi_spi:510]: Drawing from line 21 took 7ms
[14:11:06.378][V][display.mipi_spi:515]: x_low 0, y_low 21, x_high 319, y_high 41
[14:11:06.380][V][display.mipi_spi:297]: Set addr 0/20, 319/41
[14:11:06.381][V][display.mipi_spi:244]: Command 2B, length 4, bytes 00.36.00.4B
[14:11:06.384][V][display.mipi_spi:244]: Command 2A, length 4, bytes 00.00.01.3F
[14:11:06.386][V][display.mipi_spi:244]: Command 2C, length 0, bytes
[14:11:06.395][V][display.mipi_spi:532]: Write to display took 17ms
[14:11:06.397][D][display:428]: Display update running
[14:11:06.405][V][display.mipi_spi:510]: Drawing from line 42 took 8ms
[14:11:06.406][V][display.mipi_spi:515]: x_low 0, y_low 42, x_high 319, y_high 62
[14:11:06.408][V][display.mipi_spi:297]: Set addr 0/42, 319/63
[14:11:06.410][V][display.mipi_spi:244]: Command 2B, length 4, bytes 00.4C.00.61
[14:11:06.412][V][display.mipi_spi:244]: Command 2A, length 4, bytes 00.00.01.3F
[14:11:06.413][V][display.mipi_spi:244]: Command 2C, length 0, bytes
[14:11:06.424][V][display.mipi_spi:532]: Write to display took 17ms
[14:11:06.426][D][display:428]: Display update running
[14:11:06.434][V][display.mipi_spi:510]: Drawing from line 63 took 8ms
[14:11:06.435][V][display.mipi_spi:515]: x_low 0, y_low 63, x_high 319, y_high 83
[14:11:06.437][V][display.mipi_spi:297]: Set addr 0/62, 319/83
[14:11:06.440][V][display.mipi_spi:244]: Command 2B, length 4, bytes 00.60.00.75
[14:11:06.440][V][display.mipi_spi:244]: Command 2A, length 4, bytes 00.00.01.3F
[14:11:06.443][V][display.mipi_spi:244]: Command 2C, length 0, bytes
[14:11:06.452][V][display.mipi_spi:532]: Write to display took 17ms
[14:11:06.454][D][display:428]: Display update running
[14:11:06.471][V][display.mipi_spi:510]: Drawing from line 84 took 8ms
[14:11:06.471][V][display.mipi_spi:515]: x_low 0, y_low 84, x_high 319, y_high 104
[14:11:06.471][V][display.mipi_spi:297]: Set addr 0/84, 319/105
[14:11:06.471][V][display.mipi_spi:244]: Command 2B, length 4, bytes 00.76.00.8B
[14:11:06.471][V][display.mipi_spi:244]: Command 2A, length 4, bytes 00.00.01.3F
[14:11:06.471][V][display.mipi_spi:244]: Command 2C, length 0, bytes
[14:11:06.479][V][display.mipi_spi:532]: Write to display took 15ms
[14:11:06.480][D][display:428]: Display update running
[14:11:06.489][V][display.mipi_spi:510]: Drawing from line 105 took 9ms
[14:11:06.490][V][display.mipi_spi:515]: x_low 0, y_low 105, x_high 319, y_high 125
[14:11:06.492][V][display.mipi_spi:297]: Set addr 0/104, 319/125
[14:11:06.494][V][display.mipi_spi:244]: Command 2B, length 4, bytes 00.8A.00.9F
[14:11:06.496][V][display.mipi_spi:244]: Command 2A, length 4, bytes 00.00.01.3F
[14:11:06.498][V][display.mipi_spi:244]: Command 2C, length 0, bytes
[14:11:06.507][V][display.mipi_spi:532]: Write to display took 17ms
[14:11:06.509][D][display:428]: Display update running
[14:11:06.517][V][display.mipi_spi:510]: Drawing from line 126 took 8ms
[14:11:06.518][V][display.mipi_spi:515]: x_low 0, y_low 126, x_high 319, y_high 146
[14:11:06.520][V][display.mipi_spi:297]: Set addr 0/126, 319/147
[14:11:06.521][V][display.mipi_spi:244]: Command 2B, length 4, bytes 00.A0.00.B5
[14:11:06.524][V][display.mipi_spi:244]: Command 2A, length 4, bytes 00.00.01.3F
[14:11:06.526][V][display.mipi_spi:244]: Command 2C, length 0, bytes
[14:11:06.535][V][display.mipi_spi:532]: Write to display took 17ms
[14:11:06.537][D][display:428]: Display update running
[14:11:06.545][V][display.mipi_spi:510]: Drawing from line 147 took 8ms
[14:11:06.546][V][display.mipi_spi:515]: x_low 0, y_low 147, x_high 319, y_high 167
[14:11:06.549][V][display.mipi_spi:297]: Set addr 0/146, 319/167
[14:11:06.550][V][display.mipi_spi:244]: Command 2B, length 4, bytes 00.B4.00.C9
[14:11:06.552][V][display.mipi_spi:244]: Command 2A, length 4, bytes 00.00.01.3F
[14:11:06.554][V][display.mipi_spi:244]: Command 2C, length 0, bytes
[14:11:06.563][V][display.mipi_spi:532]: Write to display took 17ms
[14:11:06.573][D][display:428]: Display update running
[14:11:06.575][V][display.mipi_spi:510]: Drawing from line 168 took 9ms
[14:11:06.577][V][display.mipi_spi:515]: x_low 0, y_low 168, x_high 319, y_high 188
[14:11:06.578][V][display.mipi_spi:297]: Set addr 0/168, 319/189
[14:11:06.580][V][display.mipi_spi:244]: Command 2B, length 4, bytes 00.CA.00.DF
[14:11:06.582][V][display.mipi_spi:244]: Command 2A, length 4, bytes 00.00.01.3F
[14:11:06.584][V][display.mipi_spi:244]: Command 2C, length 0, bytes
[14:11:06.593][V][display.mipi_spi:532]: Write to display took 16ms
[14:11:06.595][V][display.mipi_spi:537]: Total update took 255ms