Mod Age of production, transmitter can be placed without purple concrete.
Same for singularity beacon from Krastorio 2.

Are you in editor mode when this happens? If not, I can't reproduce it. Which mods touch the EARS-beacons?

No, during normal online or offline sessions. Mods tested: Krastorio 2 spaced out (singularity beacon), and Age of production (transmitter). The last has 2 beacons, transmitter and quantum stabilizer. Transmitter with E.A.R.S. can be built with simple left click without energetic concrete, shift+click is trying to place it with e-concrete. Same for singularity beacon. In the same time quantum stabilizer can not be built without energetic concrete.

You have some other mod installed that overwrites the placement rules. With k2so + aop + rabbasca installed I can not place those two beacons with E.A.R.S. on tiles that are not energetic concrete.
Both are not modified by any other mod than Rabbasca for me. When hovering over the built structure, the tooltip says:
Transmitter [with E.A.R.S]
○ Rabbasca
Must be placed on [...]

If yours says ○ Rabbasca > SomeOtherMod, then SomeOtherMod is overwriting something, for example the placement conditions.

Ok I found it now, too. It is caused by maraxsis modifying the original beacons. Will see what can be done about it.