Praise be to Allah.
Plant-based meat is a type of food that is made from plants such as soya, from which a product that resembles meat in appearance is manufactured.
Plant-based meat is in fact made of plants, except that it is been manufactured in a certain way so that it resembles meat from animals.
This meat is halal so long as it is manufactured from halal plants, and all plants are halal; no plants are haram except those which are harmful or intoxicating. This is according to the consensus of the scholars.
Ibn Hazm (may Allah have mercy on him) said:
[The scholars] are agreed that all grains, fruits, flowers and gums, and everything that is extracted from them, so long as it does not come under the heading of nabeedh (fermented drinks) that we have mentioned in the chapter on drinks…
And so long as none of these things are toxic, then they are halal.
End quote from Maraatib al-Ijmaa‘ (p. 150).
As for things other than animals, that which is impure (najis) is not permissible, because it comes under the heading of khabaa’ith (unclean, evil things), and it is not permissible to eat pure (taahir) things that cause harm, because Allah, may He be exalted, says (interpretation of the meaning): “And do not kill yourselves” [an-Nisa’ 4:29].
So what is permissible is that which does not cause harm, such as grains, fruits and other crops, because Allah (may He be exalted) says: “and makes lawful for them the good things” [al-A‘raf 7:157]; all of these come under the heading of the good things. Moreover, there is consensus on that and there is no difference of opinion concerning it.
End quote from al-Bayaan (4/511).
What matters is the reality of things, not their names. So regardless of whether people call it meat or they call it plants or plant-based, the reality is that it comes under the heading of plants.
Ibn al-Qayyim (may Allah have mercy on him) said:
What matters is the reality of things, and the ruling is to be based on that. The reality of things is the basis on which they are to be deemed permissible or prohibited. Allah, may He be exalted, does not look at their outward forms and what people may call them; rather He looks at their reality and their essence.
End quote from I‘laam al-Muwaqqi‘een (5/175-176).
And Allah knows best.