Have a read of this - https://www.easyposturebrands.com/blogs/articles-1/8-ways-to-stop-right-leg-pain-while-driving
Also, it might be worth seeing a physio, you may have another issue that is exacerbated by driving. Life causes tight muscles which may not exhibit pain except under certain circumstances. A few sessions may sort you out. If the seat has been okay before, chances are that it is still okay.
Home working and long driving are one of the 'modern' syndromes of back and hip issues, and general weakness in these areas, due to the muscles being overly relaxed for long periods, lock down exacerbated the issue for many also, for example, the abductor is a really key muscle, it drives a lot of movement and with other muscles gives you good strong stability, and normal day to day walking, and stairs is normally enough for most to keep in enough shape and strength to avoid issues, but prolonged driving and sitting will eventually shorten that muscle and a bunch of 'niggles' develop as balance of that part of body becomes a bit disparate. Its not an injury that you feel happen, it becomes chronic over time, and only way to resolve is regular exercises that focus on that area, increase of activity and lessen desk and where can driving for long periods.
Not actually saying its this, it could just be you have faulty seats where something has given way, but having had 9 years of driving in MK 7/7.5 Golfs seats have never been an issue for me, and there might be another cause and that some increase in strengthening lower body might remove. Again might not be applicable to you, but this modern phenomenon is definitely a thing