Since you have been previously been "Living with flushing and overflow problems for years." I would guess it has to do more with a member of the family than the toilets.
It's nice to hear that the new toilets have at least not overflowed. Paper is the most common problem that people have. You may want to consider adding a bidet seat to reduce paper. You can get a nice one with a drying fan too. Terry

: My family is cursed with flushing problems! We recently installed Toto Drake toilets in two bathrooms after living with flushing and overflow problems for years. The problem has been minimized, but not eliminated. On a few occasions, most recently last night, both toilets have gotten clogged, but thankfully don't overflow. This seems to happen when my daughter uses the toilet and I suspect she uses a lot of toilet paper. I have not come across reports of problems with Totos and wonder if it just happens in my house or if others have had similar problems.

• Bidet seats