Tax rules in Ireland are different, but regarding VUSA - to the best of my knowledge - you’ll see no difference. This ETF will suffer the same tax treatment - as far as I know - no additional tax.
That said you need to be mindful of the ‘UK Reporting Status’ to ensure ETF sales (outside of tax wrappers) don’t suffer Income Tax rather than Capital Gains. VUSA has Reporting Status so you’re fine.
Also bear in mind that VUSA declares and pays dividends in USD. That leaves you (at least minimally) exposed to FX rates as FT will convert for you at the prevailing rate.
Ireland does impose a dividend withholding tax. But to my knowledge it does not apply to ETFs. But were to to invest in DCC or CRH, for example, you might find you loose 20% of the dividend. These are reclaimable via a similar mechanism to the US W-8BEN system. Back in the day the system to reclaim Irish tax was painful to the point of not wanting to bother. Interesting to know what the reclamation system looks like these days are if Freetrade reclaim on your behalf. My guess would be it’s not worth their time, but you never know.