It is an old-time bug still present in 2023 I've experienced it in around 2016 when I encountered with the anamorphic shooting for the first time.
When the adaptive resolution is switched on in the compositing panel, anamorphic footage that is within it flips and stretches itself while scrubbing or dragging playhead.
Steps to reproduce:
1) Insert any red anamorphic footage like 6k with 12:5 squeezing ratio (could be any different from square pixels) into the new composition
2) Set to adaptive resolution in the composition panel
3) try to grab the timecode to shift time or grab the playhead and drag
4) Also you can either try different render resoulutions in composition panel or in Edit -> Preferences -> Preview and try changing the adaptive res limit like to 1/16 and try to srub the footage and see how differently it behave with different limits...
The attached is a screengrab of how it goes