The strawberry test shows more of a lack of knowledge in the tester than it does in the LLM. LLMs don't see letters, they see tokens. When you type the word "Strawberry" what it actually sees is:
[3504, 1134, 19772]
Each token represents a chunk of the word. It'd need to separately memorize how many of each letter are in each token for it to just "know" how many "R"s are in there. That's why modern LLMs either reason it out by spelling out the word letter by letter, or just writing a short script in an execution sandbox to count the letters that way.
Calling out LLMs for being poor at spelling is like challenging a colourblind person to say what colours a bunch of fruit are. They can often figure it out by other means but it's more challenging than you'd think and it's not a sign of poor intelligence if they get a few wrong.
Except I also explained how modern LLMs get around that problem. They're not actually that easy to trip up.