A little help, please.

The chandelier in the dining has functioned fine ever since we've been here. Almost 20 years.

It's got five bulbs. Lately we've been using GE Refresh LED daylight bulbs. A15. They've been fine and as soon as I turn it on it's daylight bright.

Wednesday when I turned it on all the bulbs were uniformly dim. They gradually got brighter, but not as bright as before.

Yesterday (Thursday) I turned it on and it was immediately bright.

I googled the issue and AI said it might be a problem.

What am I looking at? Can I determine anything if I put a multimeter on it?

Thanks in advance.

It can't hurt to put a meter on it . Check it on the switch and that will give you an opportunity to check the connections there .

Could be the LED bulbs. If you’re not seeing dimming on other fixtures, then the circuit is not the issue. LED bulbs are not they are cracked up to be and don’t last as long as advertised. I would recommend trying a different brand of bulbs.

^^^ But odd that all five would start to fail at the same time.

Loose neutral.
Check all connections both circuit from breaker to light fixture.

If the light switch only controls the chandelier, I would suspect the switch itself is bad. It has a moving part, will eventually wear out.

Easiest thing you can do is swap switch(es), and verify good neutral connection at switch(es).

I'd say if that doesn't solve it contact a professional depending on your confidence level at being an electrician.