When replacing the Tonemap using a Post Process material, the Post Process Volume's Bloom Intensity can only be turned on or off, without varying degrees of effect.
Reported in version 4.25.3(CL 13942748). Tested in versions 4.25.3 and 4.24.3(CL 11590370) with same result.
Results: The tonemapper will work, except Bloom Intensity no longer works.
Expected: You can set Bloom Intensity to 0 and it will turn off, but setting it to any other number will turn it on, but you'll have no control over the intensity.
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-100344 in the post.