Is are powder stain removers any good?

[NoisyBrain]

I think this is the right place to post this, haven't ventured into this part of MN before!

I have a bikini which has a blue pattern on a white background. Except the white background is now mostly yellow thanks to suncream (and sweat probably, yuck) from last year's summer holiday. I only bought it last year and had hoped to get a bit more wear out of it as it fits like a dream!

I googled tips for restoring white swimwear to whiteness and have tried soaking it in a baking soda solution, which did nothing. I'm now looking at buying a whitening powder such as Vanish. Is it any good, or can anyone recommend a tried and tested home remedy that actually works?
TIA.

Oops just spotted the typo in the title

Have you tried hanging it outside to sun bleach?

My go to stain removers are

Astonish/Vanish soap bar, wet item with cold water and rub in well. Let sit for a while then wash.
Ace bleach, pour on, let sit according to instructions then wash (sitting for too long will fade the fabric)
Vanish/Aldi powder bleach. Soak as per instructions then wash.

Petitprince no I've not tried that. If we get more than 5 minutes of sun before July I'll give it a go

Thanks FrogFairy. I''m just off to Lidl. If Aldi do a Vanish equivalent I'd guess it's likely they also do. I shall investigate.

Please report back on Lidl stain remover! In my experience vanish powder is the only thing that gets stains out of my toddlers bibs. And only the crystal white vanish powder also which is £££. Have tried others with no success.

Well, like a dozy plank I forgot to look for the stain remover in Lidl!

I may just bite the bullet and buy the pricey Vanish stuff in town tomorrow (as Lidl is a whole 5 miles away). In the meantime, I found some Vanish spray on stain remover in the back of the cupboard so I've liberally sprayed that on the bikini and stuck it in the wash to see what happens. I'm not overly optimistic...

Do not use back to white by Dr Beckman .
I used some for whit towels. It worked brilliantly. Too brilliantly. I accidentally put a cream towel in to, which came out white too.
The bikini will be ruined.

Not sure about Lidl but Aldi tubs of powder are sold as special buys every couple of months so might be worth grabbing then.

Bubblysqueak thanks, I'll avoid that one!
FrogFairy There's an Aldi about 5 miles in the other direction from Lidl so may give that a go.
Thanks all.