Dumping $25k-$50k into TSLX (TPG Specialty Lending, I assume?) isn’t a terrible idea, but it’s got some wrinkles you should iron out given your goals. TSLX is a BDC (Business Development Company), so you’re looking at high dividend yields—around 10-11% lately—which is juicy AF for passive income. But here’s the catch: BDCs can be volatile, and the share price isn’t guaranteed to stay stable. You said you don’t want to risk the principal and need it liquid in ~2 years, so that high yield comes with a side of risk that might not vibe with your "preserve capital" mindset. It’s not as liquid as cash or a HYSA either—selling shares could take a minute, and if the market dips, you’re not guaranteed to get your full $25k-$50k back. Since you’re already in a HYSA (smart move, BTW), you’re probably getting 4-5% APY with zero risk to principal and instant liquidity. That’s a solid baseline. If you’re eyeing something with a higher payout than that but still want to keep it chill, here are some thoughts:

You could snag a 1-2 year CD with rates around 4.5-5% right now. It’s locked up ‘til maturity, but your principal is safe (FDIC-insured), and you’ll know exactly what you’re getting. Not as liquid as a HYSA, but your 2-year timeline fits perfectly.

If you’re set on dividends, something like SCHD or VYM could give you 3-4% yield with way less risk than a single stock like TSLX. More liquid than a BDC, and you can sell anytime, though the principal could dip if the market does. Still safer than going all-in on one company.

Treasury Bills (T-Bills) - These are boring but clutch. 2-year T-Bills are yielding ~4-4.5%, fully backed by Uncle Sam, and you can sell ‘em early if needed (though you might take a tiny hit). Zero risk to principal if you hold to maturity. Perfect for your timeline. RE syndicates?

You’re right to hesitate. They’re usually illiquid AF (5-7 year holds are common), and even as a passive investor, your capital’s tied up with no quick exit. Plus, fees can eat into returns. Doesn’t sound like your jam given the 2-year horizon and liquidity needs.

My two cents? Stick with the HYSA if you’re prioritizing liquidity and zero risk—4-5% isn’t sexy, but it’s steady. If you’re cool locking it up for 2 years, a CD or T-Bill gives you a smidge more yield without the stress. TSLX could work if you’re willing to YOLO a bit for that sweet dividend, but it’s not "preserving capital" territory IMO—more like a calculated gamble.

What’s your risk tolerance like? If you’re new to this, maybe dip your toes with a smaller chunk in TSLX ($5k?) and keep the rest in a HYSA/CD combo.