Hello /an/ Since some months my lemon tree has some orange fruits

there's like 20+ possible causes, but they're probably just over-ripened.

is this the first time it's carrying fruit?

>>2041315
No. The lemon tree is about 15 years old and always had lemons on it in past years. The orange fruits happen regulary last time.

>>2041322
are all of the fruits like this?

>>2041328
Just the orange one.
The lemons are normal.

>>2041336
your lemon tree is probably grafted on an orange, and the graft started producing branches.

take a picture of the trunk.