Hello,
I have a question regarding the support duration for the theme_classic that is built into CORE. I seem to recall coming across a specific date/version for Moodle, but I can't seem to find that information now.
We haven't defined a timeline for this but it will not be before the next LTS (Moodle 4.5). Once the decision is made there will be plenty of runway for all customers to transition, this also has implications for a number of large institutions who have themes based on classic so before we get to that point we need to do an impact assessment. Hope this helps.