i am fascinated by how english native speakers confuse you're with your but non native dont usually have problems.
in spanish is normal to change the prounouns (le la los la) grammar rules depending of the region of spain making talking with people a little confusing https://en.wikipedia.org/wiki/Le%C3%ADsmo
not rly a mistake but in russian adjectives agree with nouns in gender. Take любой (any). It can be любой (default, masculine), любая (feminine) or любое (neuter). Adjectives also agree in case, of which Russian has six. When the masculine adjective is declined in the genitive or accusative cases (also when the neuter is declined in the genitive), it takes on the ending -ого, so любого. Or transliterated using latin "lyubogo". However the г there is not pronounced like hard g. It is pronounced like v or в in cyrillic. This is done for easier flow and so it doesnt sound awkward. It is technically a mistake but when it's long been established can you rly call it a mistake at this point?
ps there are also colloquial misspellings like spelling words as they're pronounced, for example раён - act. spelling район (neighborhood, district), канешно - конечно (of course, certainly). I would say this is akin to english textspeak like h8 or gotchu or inb4