Yes, it's a fact: you can generally only use two phone lines, whether eSIM + eSIM or SIM card + eSIM.
Several eSIM profiles can also be saved and the SIM card does not have to be removed if you decide to use two eSIMs (perhaps temporarily for a trip?).
You can deactivate unused (e)SIMs temporarily via a software switch. Very convenient.
Unfortunately, information on this topic is very scarce and bad journalists make complicated research even more difficult with their misleading articles.
“Thanks” to Mishaal Rahman and a German “journalist” who copied him, in March 2023 I wasted my free time and completely unnecessarily flashed my Pixel 7 Pro with GrapheneOS back to stock Android 13 and tried under stock Android to see if dual eSIM (MEP) would work.
However, this could not work because at that time it was only possible with a very specific developer version of Android 13. Mishaal Rahman did not mention this in his article and the other journalists only copied from him. :-(