It’s worse than that, a standard (cheap) dc supply as used in a LED lamp uses a capacitor to limit the current as the capacitor charges and discharges on the AC cycle it lets a small amount of current flow, but if the AC signal is not smooth then the capacitor and the rest of the circuit get the electronic equivalent of jerk on every cycle, which stresses everything and will rapidly lead to failure.

You can tell how it’s wired by the fact the original dimmer was between two blacks.

I’m not saying to assume that white is neutral for the purpose of fitting a smart switch here, I’m saying assume white is neutral so you don’t wire a switch to short it to live. The new switch needs to be wired like the old dimmer, not like the picture in the link at the start of this sub thread.

The wiring is line in/line out which is the two twisted lives (black) as well as a switched live out (black alone).

The whites are the neutrals.

Wiring a switch to bridge between live and neutral (as it would be if they copied the pictures) is a problem

Like that in layout, not like that in colours.

If you wire the switch like that it will go bang