They may be in need of a bit of a routine change. Their A times are on the lower side for their age, but neither of their naps is really restorative (1.5h or more) so either UT or OT could be the culprit.
I would try pushing out their morning nap a little - add ten mins to A time, hold for 3-4 days, then increase again if you're not getting a 1.5h nap. If you get the longer nap, try the same A time again for the second A and you may need to wake them from the second nap so they are tired enough for BT. A typical routine might look like:
WU 6am
Nap 10-11.30
Nap 15-15.45/16.00
BT by 7pm
The alternative is to cap their morning nap shorter and bring the pm nap earlier e.g something like
WU 6am
Nap 9-9.45/10
Nap 1-3
BT 7pm
You want to keep the day to a max 13h so if you're getting resistance at BT, you need to shorten your short nap further to fit everything in. There's a useful link here:
10/ 11mo sleep gone wonky? Read this first!