try recalibrating the EC pen and re-measure... ppm is calculated differently depending on equipment, so it's better to use EC values when speaking with ppl that could be around the world, fyi. tds pens measure ms/cm^3 or some shit like that lol... then a factor is applied to give a "ppm" reading.. that factor will be different depending on equipment. they don't directly read ppms.
5000 would be well-beyond deadly. Could also be exaserbated by low water levels... less water = less volume, which is the denominator in a concentration equation.
5000ppm would definitely be causing some lockout and major symptoms would be present on the leves. These look fairly light green but probably darker in normal lighting - realtively healthy except for the droop.
i can also tell by the drying pattern of the surface that you probably do not have good irrigation habits. odd things do occur, though. how much fertilizer you need for soil or some pre-amended bio365 or whatever tit is is like riding a bike. numerous variables impact exact need even if someone uses same stuff, but finding diaries that use the same products will give a good staring point. take notes and avoid symptoms 'next' time or try pushing harder till you have to dial back... it's like learning to ride a bike.