Unknown ugly white marks on wooden dining table (water, heat or something else?)

Hello, first time poster. I have tentatively purchased this table unseen in person. I love the timber however there is some concerning white surface marks. I have been told it is from pot plants, but the larger rectangular one looks like a hot pan outline. I have done some research into removing water and heat stains, but I’m unsure if that’s even what this is and how serious the damage is. Any ideas much appreciated, as I will be attempting to remedy this myself as a totally amateur woodworker.

The hot iron technique seems to be a very popular and effective method to remedy watermarks, so that’s the first method I plan to try unless advised otherwise. However I have found conflicting information re steam vs no steam.

Mohawk spray appears to be another option, however there are no local stockists and I’m not sure this is the suitable product for the damage.

I really hope to not need to sand it down and restain as this makes me nervous given my ability.

If this damage is too severe I can still back out of the sale. It seems like a high quality set with (seagrass?) rattan chairs, what do you think?

Any input appreciated. Thanks in advance.