[Doom64hunter]

Demonstrations of the bug in action (godmode was turned off):

Drones (E2L3): https://streamable.com/ea7rb

Tripmines (E3L2): https://streamable.com/v87vu

Shrinker (E1L4, second shrinker turret): https://streamable.com/0p878

The problem originates from revision r8079: "Fast A_RadiusDamage()"

It seems that the changes to A_RadiusDamage() inadvertently caused its behavior to change, while the commit message itself indicates that this was supposed to be a performance improvement.
Namely, it appears that explosions, and by extension the shrinker blast, can no longer hit actors past certain sector boundaries.
I'm not exactly sure what the conditions for this are, but the videos above may give some indication on which sectors are affected.

[Doom64hunter]

Explosion radiuses seem to behave correctly across sectors again as of r8573, and the spots seen in the videos above are fixed now.

However there still seems to be some inaccuracy with the shrinkblast radius.

Here's some footage from E1L5, The Abyss:

DOS Duke 3D: https://streamable.com/jd9ds
eduke32 r8573: https://streamable.com/ec2bj

If the player is hit at a certain height, the shrinkblast does not affect him. This just happens to be the case at the height of the platform of The Abyss where you activate the shrinker.
It does not depend on which sector the player is in, if he is low enough he won't get hit by the blast, as demonstrated in the video. This also started with r8079.
In DOS Duke 3D it does not seem to matter at which height the player gets hit.

[TerminX]

This is fixed now.