Dear Gardeners,

I am having a strange issue with almost all my lemon tree plants that i wasn't able to identify simply by looking for photos on the internet. At first i would think of spider mite or leaf miner damage, but there is no clear sign of any white-silver stuff on or underneath the leaves. These plants were overwintered in a garage under cfl artificial lights (6500k, cool) in a temperature ranging from 14 C up to 20 C. They were repotted in citrus soil before moving them in the garage last year. I enclose some photos below.

Looks like insect damage, but it then should be invisible...
The tip of the leaf stems on one of my plants became woody, is it normal..?
New growth is yellowish, which could be ok to some extend, but its consistency is just not smooth, it's rather bumpy and uneven. Parts of the leaves are missing--> (insect damage?)
Again, bumpy, uneven leaves with woody stems on the tips, where it joins to the main stem. This apparently causes droopy leaves because of possible nutrition deficiency due to the lack of "green surface" transmitting nutritions (?) But i really have no clue.

Uneven surface with some yellowing and missing parts.
Yellowing and missing parts, could it possibly be sunburn?
Deformation and some bug infestation? But i had never ever found insects on or under the leaves...
Close-up picture. The main middle shaft of the leaf becomes brown and woody sometimes
Again
And again.

I am ready to provide more pictures, but thats the maximum number of photos that can be uploaded at once.

I would be grateful for any opinions,
A.S.