What you have is "plasticizer migration." The chemicals in the placemat that keep it soft and flexible has migrated into the finish and done the same there. The damage is in the finish, not on the finish.

If the damage is not too bad, you might be able to buff it out with some 0000 steel wool. If there is a dark toner (finish with color in it), it might lighten the spot some. You can get more lacquer finish in aerosol cans and if you can get a good match on the color, also toner in aerosol.

There is also a chance the damage is all the way through the finish, in which case it's more difficult.

A good touch-up technician may be able to recover for you.

It would be worth trying in an attempt to avoid stripping and refinishing the whole top.

Steam cleaner is not good -- stop that now. You may have damaged your table's veneer or finish using that.

Thanks so much _ I will try the steel wool tomorrow.

I know the steam cleaner did not help the situation but I just tested it with the steam cleaner.

Good to know that lacquer finish comes in aerosol cans thanks again for the info

Pat