Decreasing brush size with [ key deletes layer in PS

MacBook Air M1 ;  macOS 14.1.2 (Sonoma);  PS CC 25.x

Open image file, copy layer, choose a brush tool while on new layer .  Then - - - 

      pressing the right bracket key repeatedly enlarges the brush (as expected), but

      pressing the left bracket key repeatedly reduces the bush size the firt two times, and then deletes the new layer.

I have used the bracket keys as this kind of shortcut for years.  Sometime in the past few months I started getting the delete-layer-on-the-third-consequtive-use behaviour.  

It happens every time, and with any function that uses these bracket key shortcuts.

It has happened with several updates of PS-beta as well as PS 2024.

It is acting as though there were some kind of background shortcut that replaces three left brackets in a row with something PS interprets as a delete-layer command.