"much" is an unqualified and unjustified word here. It definitely happens but this would at most affect a tiny fraction of donor money.

Many of the NGOs have strict no-bribery policies, else they would not receive support from bodies like the EU (which is the biggest humanitarian donor on the planet).

In some cases the choice may be between "letting people starve" and "feeding people but the local warlord extracts some benefits" but these are rare and only the worst crisis contexts (think South Sudan, DRC).

Yes, but it's important to note that just because a lot of aid is ineffective doesn't mean it all is. If you want to give to very poor people and be confident most (85%+) actually gets to them I encourage you to take a look at https://www.givedirectly.org/. Full disclosure, I'm an unpaid trustee of the UK sister charity

I do some work in Africa and that's not what i've seen. The NGOs have their own separate supply chains and are quite resistant to corrupt officials and local criminals. The problem with NGOs is that they're mostly regular business masquerading as 'aid' and out competing local businesses who dont have access to their infrastructure and subsidies. There's actually much more demand for NGOs from the West than from their recipients. African governments are trying to clamp down on NGOs, but there's a lot of pressure from the west for the status quo.

If the implication is true…

Shouldn’t people stop helping further entrench these shady practices?

If Ugandan decision makers know the people will effectively always be underwritten to receive some bread and water… no matter what happens…

Then what exactly is stopping them from piling on more and more nonsense?

Which is why, naturally, the American Red Cross is the gold standard for NGO donation efficiency.

A polished website and audited reports don't always tell you whether aid is reaching people effectively on the ground