Hello thereI need some help with this. I have growed this from seeds with no clue what it is. It developed well indoors but now it is getting yellow leaves and I don't know why. For what I know it could be Delonix regia or Albizia julibrissin. First one should be kept indoors in winter, second one needs more coolness If it would have flowered yet it would be easier to determine... Any suggestions are welcome

where did you get the seeds from? No label? I have no more idea than you what it is, or where you are. Leaves on deciduous species will turn colour in autumn, so it could be natural but unless you identify the species it is a bit difficult to say more.

Google Lens should be able to determine the species.  There are several plant specific apps that do the same.