In order to export square video out of Premiere Pro 2022 just export the sequence as usual and in the export settings (under 'Basic Video Settings' uncheck the box for Width and Height) and change the video dimensions to 1080x1080 (for FullHD videos) or equal dimensions for 4K videos accordingly.
Now in the upper left corner set the 'Source Scaling' to 'Scale to Fill'
Alternatively, you can change the dimensions of the sequence you are trying to export. Go to 'Sequence Settings' and change the dimensions here. If the 'Frame Size' is greyed out just set the 'Editing Mode' to 'Custom'. Now the dimensions should be accessible.
When you export the video now you don't have to tweak any settings will be square already and you can just export your video.