Problem:
Putting down charcoal scrubbers gives -135 pollution/min.
Surrounding a scrubber with beacons and inserting level 1 modules ends up with a scrubber with roughly -30 pollution/min.

In other words, the modules will increase the pollution per min towards 0 instead of lowering it away from 0.

Expected behavior:
Scrubbers surrounded by beacons filled with pollution reduction modules should further decrease (the already negative) amount of pollution reduction the scrubber does. So, with a limit of 80%, I'd expect a -135 pollution/min scrubber to reach roughly -243 pollution/min.
This is, of course, me thinking the reverse about this, where -135 is the default of 100% and the 80% additional reduction.
If going by the tooltip, the effect is correct, but using the beacons makes no sense.