Why consumer is informed of balance insufficient when there is actually enough money in consumer's account?

Card issuer limits the amount of single, daily, monthly or annual transaction. For further details please refer to official information provided by the issuer. ① Banks’ limits for UnionPay online payment https://online.unionpay.com/static/help/detail_38.html ② WeChat Pay bank card transaction limits http://kf.qq.com/touch/sappfaq/151210NZzmuY151210ZRj2y2.html?platform=15&ADTAG=veda.weixinpay.wenti&code=033JtWUJ0Qsge826i9VJ0U34VJ0JtWU9&state=123&from=singlemessage&isappinstalled=0 ③ Alipay debit card quick payment limits https://cshall.alipay.com/lab/help_detail.htm?help_id=419480