The same thing happened to our pine kitchen table. As others have suggested, we used to periodically sand it back to the bare wood using an electric sander, then seal it with a coat of matt varnish, finish off with wax lightly rubbed in with fine wire wool before buffing up with a cloth.
you don't need a pro. I am doing ours as we speak with a small hand sander. Start with sandpaper grade 100, move up to 180 and finish with 240. I will be oiling with 3 coats of osmo top oil which we have used on our worktops. Gives a hard wearing surface with a slight sheen.
About 10 years ago, DH and I splashed out for a reclaimed wood table and 6 chunky chairs to match. I think it's oak.
It is my pride and joy. It's scarred, rustic and hosts my large hungry family. DD's also live around it, doing homework, colouring, crafting, plasticine moulding etc. I do my marking there. It's THE furniture item of our daily life.
I've used kitchen spray to clean and disinfect it but now after years of use, the varnish has disappeared in patches, and the rest feels really tacky and sticky. Paper work literally sticks to it and it's looking terrible. I want it back to it's happy normal self but we have no idea what to do. HELP!