Rails 6.1 gives extra precision value on upgrade

Question

I was upgrading the Ruby on Rails application from 6.0 to 6.1. When checking the start_date which is having having extra precision value when it comes to 6.1

2.7.0 :001 > User.last.created_at
  User Load (11.4ms)  SELECT "users".* FROM "users" ORDER BY "users"."id" DESC LIMIT $1  [["LIMIT", 1]]
 => Sat, 10 Oct 2015 11:36:14.042865000 UTC +00:00 
2.7.0 :002 > 

When it comes to 6.0, we are no longer has this issue, it is having below values.

2.7.0 :001 > User.last.created_at
  User Load (2.0ms)  SELECT "users".* FROM "users" ORDER BY "users"."id" DESC LIMIT $1  [["LIMIT", 1]]
 => Sat, 10 Oct 2015 11:36:14 UTC +00:00 
2.7.0 :002 > 

Which is causing all the specs to fails. The database used is postgres and I have research on this and there is not much of a fix on this. The field is timestamp field and it is not a precision value encoded.