I thought I would try the latest kernel 5.15 and installed it through manjaro settings manager.
I had several sudden and unexpected crashes ( after a couple of hours use). It seems this is not an isolated case and saw a post on the Manjaro forum which seemed to confirm this.
I reverted to 5.14 and all is fine . I will wait for developments.
Ref: I run Intel Core i5 with integrated graphics so no Nvidia problems are involved