The main problem now is that people on coaches (mainly university students off for a weeks skiing) have to get off the coaches and have their passport stamped. Obviously that's 50+ people per coach who in the past would have just been waived through.
The reason they have to get off the coach is that as non EU residents you are only allowed to spend 90 out of any 180 days inside the Schengen zone. The computer system to monitor this isn't yet up and running (and hopefully never will be!), so the only way they know how long you've spent inside the Schengen zone is by counting up the in and out stamp dates. Now generally the French don't care about in and out stamps, but other countries - Germany, Austria, Swizerland - do, and having a mismatch/missing in and out stamps in your passport can cause grief, and potentially get you refused entry.
This is the first fully non Covid winter since BREXIT. Can't see things getting better any time soon when traveling at peak times over the Channel.