I have a couple elms with leaves looking like that. They are tall and in buckets growing out. If I leave them up on the benches they get blown off. So they sit on the ground. Where they don't get the best drainage,more shade and have been hit by frost a couple of times already. The ones up on the benches are perfectly healthy.
Probably fungus or too wet or a combination of both plus getting blown over still.
That's my problem.
How wet is your soil?
Does it get full sun for as long as possible?
Is there adequate air flow?
For mine,I'm not worrying. They'll be dropping leaves and getting ready for the long freeze.
Elm leaves turn a buttery yellow in fall if winter doesn't hit them first. I don't always get the yellow that comes naturally. Sometimes they just freeze off but when conditions are right they should be this color.